September 1, 2011

Breast cancer patients over the age of 60 with early-stage, hormone-responsive small tumors who forego adjuvant endocrine, also called hormonal therapy, are not at an increased risk of mortality compared to women of the same age without breast cancer, according to a study published Aug. 31 in the Journal of the National Cancer Institute.

The use of hormonal therapy has increased in breast cancer patients overall, and the 2009 St. Gallen International Breast Cancer Conference recommended hormonal therapy for almost all patients with hormone-responsive disease. But previous studies have not identified patient subgroups that might not need adjuvant therapy or those who without the therapy would have the same longevity as women in the general population.

To identify patient sub-groups who may or may not benefit from adjuvant hormone therapy, Peer Christiansen, M.D., of the Aarhus University Hospital in Denmark and colleagues, looked at a population-based cohort of untreated breast cancer patients in Denmark. They identified 3197 patients with node-negative breast cancer from the Danish Breast Cancer Cooperative Group, between the ages of 35 and 74. The patients were not given adjuvant hormone therapy or chemotherapy.

The researchers obtained data on the mortality rate of the general Danish female population from Statistics Denmark. The researchers then estimated the relative risk of death among women in the study compared to the general population by calculating the standardized mortality ratios, or the ratio of the observed number of deaths among patients in the cohort compared to the expected number of deaths in the general population.

The researchers found that the excess mortality rate in the patient population was highest for patients aged between 35 and 39 years and lowest for those aged 60-64 years. The relative mortality of patients compared to the general population was also greater for patients with tumors larger than 10 millimeters. The researchers write: "Age less than 60 years at diagnosis and tumor size greater than 10 millimeters were independently associated with a worse prognosis."

However, they also identified a group of low-risk patients aged 60 or older with mortality rates comparable to the general population. These patients had tumors or 10 millimeters or less and low-grade disease (grade 1 ductal carcinoma, or grade 1 or 2 invasive lobular carcinoma.) The researchers concluded that these patients might not benefit from adjuvant therapy.

In an accompanying editorial, Jennifer J. Griggs, M.D., M.P.H., and Daniel F. Hayes, M.D., of the University of Michigan, write that the study confirms findings from other studies showing that local therapy alone is adequate for treating older women with small tumors and that "adjuvant endocrine therapy does not reduce the risk of mortality in patients with very small, node-negative hormone receptor-positive breast cancer because the risk of mortality is already extremely low."

However, the editorialists add that overall adjuvant therapy is effective in reducing the risk of recurrence in the same or opposite breast and that many women will continue to take it for that reason. "Clearly, patient preferences regarding risks and benefits of endocrine therapy play a critical role in decision making, and high-quality information support is essential in these settings."